Processing modified pigmentary compositions

ABSTRACT

Anhydrous silicate minerals are employed in combination with hydrous silicate minerals to produce pigmentary compositions by admixture of said minerals in a pulverized form with an inorganic binder followed by the formation of agglomerates which are calcined to produce pigmentary compositions embodying numerous particles of the minerals bonded together and presenting internal voids and multiple light reflecting surfaces. The compositions thus produced posess light reflecting properties greatly exceeding those of the minerals from which they are formed. Morever, the pigmentary compositions are characterized by specific gravities substantially below that of the material of which they are formed whereas the water absorption characteristics of the pigmentary compositions are relatively low, permitting their use in liquid or plastic media without adversely affecting the viscosity thereof beyond that attainable with other pigments.

'lilite tats atet 1 Ferrigno i 1 PROCESSING MODIFIED PIGMENTARY COMPOSITIIONS [76] Inventor: Thomas Howard Ferrigno, 29

Clover Hill Cir Trenton, NJ.

22 Filed: July 5,1973

21 Appl.No.:376,461

Related U.S. Application Data [63] Continuation-impart of Ser. No. 306,926, Nov. 15,

[52] US. Cl. 106/288 B, 106/306, 106/308 B [51] lint. Cl. C094: 1/28 [58] Field of Search 106/288 B, 308 B, 309,

[56] References Cited UNITED STATES PATENTS 3,533,821 l0/l970 Landquist 106/306 Primary ExaminerDelbert E. Gantz Assistant Examiner-J. V. Howard Attorney, Agent, or Firm-Sperry and Zoda l ABSTRACT Anhydrous silicate minerals are employed in c0mbination with hydrous silicate minerals to produce pigmentary compositions by admixture of said minerals in a pulverized form with an inorganic binder followed by the formation of agglomerates which are calcined to produce pigmentary compositions embodying numerous particles of the minerals bonded together and presenting internal voids and multiple light reflecting surfaces. The compositions thus produced posess light reflecting properties greatly exceeding those of the minerals from which they are formed. Morever, the pigmentary compositions are characterized by specific gravities substantially below that of the material of which they are formed whereas the water absorption characteristics of the pigmentary compositions are relatively low, permitting their use in liquid or plastic media without adversely affecting the viscosity thereof beyond that attainable with other pigments.

13 Claims, No Drawings PROCESSING MODIFIED PIGMENTARY COMPOSITIONS This application is a continuation-in-part of copending application Ser. No. 306,926 filed Nov. 15, l972.

FIELD OF INVENTION As disclosed in said copending application for patent, novel pigmentary compositions may be produced by forming pulverized anhydrous silicate minerals into aggregated bodies of agglomerates with an inorganic binder after which the agglomerated minerals are calcined to produce products having internal voids but possessing limited porosity and presenting a multitude of light reflecting surfaces. Such products accordingly have an opacity greatly exceeding that of the minerals of which they are composed together with reduced specific gravity and limited water absorption characteristics.

It has now been discovered that pigmentary compositions having the same or even greater opacity can be produced when using amixture of anhydrous and hydrous silicate minerals. Moreover, the operations employed in producing the pigmentary compositions can be modified and simplified in some respects. Furthermore, the finished pigmentary compositions generally have improved physical properties and strength which extends their uses particularly when employed in mastic compositions, plastics or in liquid media under conditions wherein they may be subjected to intense working or shearing action which might tend to break the pigmentary compositions.

The present invention also renders it possible to employ a wider variety of minerals and mixtures thereof many of which require but little preparation for use and are quite inexpensive and readily available in large quantity.

PREFERRED EMBODIMENTS in accordance with the present invention it is still desirable to use anhydrous silicate minerals in producing the pigmentary compositions and in fact at least half or more of the minerals incorporated in the compositions should be anhydrous silicates. As disclosed in said copending application the preferred anhydrous silicate used is feldspar although it is possible to use many other anhydrous silicate minerals such as silica; alkali metal silicates such as berylium, magnesium and calcium silicates; alumino silicates; alkali alumino silicates such as lithium. berylium, barium, sodium, magnesium, calcium and potassium alumino silicates and mixtures thereof.

Such anhydrous silicates generally have specific gravities varying from about 2.2 to 2.8. They are employed in a comminuted form which may vary in average particle size from about 2 to 100 microns but preferably have an average particle size of from about 2 to microns.

The hydrous silicate minerals which are employed may be of widely varying classes and types. For example phyllosilicates consisting of two or three layer silicates such as kaolinite. serpentine, pyrophyllite, talc, mica and chlorite as well as non-swelling montmorillonites may be used. Sorosilicates such as hemimorphite, hydrous zinc silicate, lawsonite and the epidote group of sorosilicates which contain calcium and aluminum ions can be employed. Among the tectosilicates which are useful are opal or hydrous silica and the zeolite group. The amphibole group of inosilicates such as tremolite and actinolite may be used as well as perlite which includes siliceous volcanic glasses derived from alkali feldspar and silica and containing 2 to 6 percent of water.

The hydrous silicates ordinarily have a specific gravity in the range of 2 to 3 and are generally smaller than the particles of anhydrous mineral and may range in average particle size from about 0.5 to microns. The preferred size is from about 1.5 to 20 microns equivalent spherical diameter.

The refractive indices of the various silicate minerals employed in the practice of the present invention all range from about 1.43 to 1.75. When such minerals are dispersed in organic media having a similar refractive index, such as tricresyl phosphate for example, they contribute little or no opacity thereto in tests wherein the dispersion is placed in a glass beaker and a white sheet having printing thereon is viewed therethrough. However. mixtures of minerals having even slightly different refractive indices contribute to the opacity of the pigmentary compositions when used in combination in accordance with the present invention.

Although it is generally preferable to use minerals having no distinct color due to iron, manganese, etc., many colors become less pronounced or even disappear on calcining. Added reducing agents or reducing atmospheres in the calcining step also aid in producing acceptable white products. Of course, if it is the intention to produce a colored pigmentary composition as described in copending application Ser. No. 356,055 the choice of the mineral and its color will be governed by the final color of the product desired.

in any event and in accordance with the present invention the opacity of the pigmentary compositions produced is substantially greater than that of the individual minerals contained therein with the result that the refractive indices and opacities of the various minerals is of less importance than the combined effects attained by temporarily bonding the mineral particles together to form agglomerates and then calcining to form permanent bonds in the pigmentary compositions characterized by the presence of internal voids and multiple light reflecting surfaces.

The inorganic binder used to temporarily bond the agglomerates prior to consolidation in the calcining step may be chosen from three different classes. Thus, expanding lattice montmorillonites are preferred but a glassy phosphate such as the sodium polyphosphates having from 4 to I00 phosphorus atoms per molecule and described in US. Pat. No. 3,l27,238 may be used and various soluble silicates such as the alkali metal silicates of commerce including sodium, lithium and potassium silicates may be employed.

In some compositions embodying the present invention opacifying agents may be used as modifiers to impart desired colors thereto as described in copending application Ser. No. 356,055.

The proportions of the ingredients used in producing products in accordance with the present invention may be varied considerably but for most purposes they are employed in the following general and preferred ranges.

The dried agglomerates are thereafter calcined at a Compositions temperature near the melting point of the minerals con- Basic, General Preferred tained therein, say, at a temperature of from about i Max, Min Max, m l,l to l,200C for about 5 to 15 minutes for feld- 5 spar. The temperature employed and the duration of p gg Silicate 89 49 5 78 54 the calcining operation may be varied considerably but Hydmussiiicme should be controlled to assure effective bonding and M t 4925 40 20 incipient fusion of the mineral particles at their points Bmde" I 6 2 of contact without actual melting thereof. In this way Colored1 H 10 strong pigmentary compositions, which will not crumj rgf 89 40 78 49 ble or be destroyed upon subsequent handling or work- Hydrous Silicate ing, are obtained.

Cmmm i The pigmentary compositions thus produced contain Inorganic Binder i0 1 6 2 numerous intermingled particles of anhydrous and hy- H drous silicate minerals, with or without the presence of whne gsggi tt g g an opacifying agent, permanently bonded together. Mineral 88 40 73 54 The compositions may have an average size of from a 'gggs 30 I0 30 about 20 microns to l centimeter depending upon the Opacity Modifying manner in which they are formed and the use for which fif g Binder f8 i 2 g 20 they are intended. For use in thin films such as paints, for example, the pigmentary compositions may have an If desired, Small amounts of dispersing agents and average SIZG. of about 20 to 5Q microns. When used in other additives may be used in formulating the compof 'o Such as Castmgsi caunfs and sitions. in producing the agglomerates to be calcined, the the p'gmehtary oomposltlons may h Slzee of the particulate anhydrous and hydrous silicate minerals froth about 100 to 1000 mtetohs, W m e y thlek may be intimately mixed together along with any Opaci sections may be as large as l centimeter in their greatfying agent or colorant which may be used. The binder est dlmensloth may be then added to the mixture in the form ofa solu Becaus e of the presonce Internal volds or od o tion or dispersion with sufficient water to assure unithe p e g y 0f the pigmentary Composition s form distribution of the binder and adequate plasticity. 3o eubstahtlahy less than h of'the 'h o which It The resulting product may be then formed into beads, composed; the reduetloh speelhe gravlty y h pellets, spheriods or any suitable shape containing nufrom about 5 to P t t other hand e P merous particles f the Silicate minerals adhering mentary compositions exhibit minor surface porosity as gether. Alternately, agglomerate formation may be acdemonstrated by the fact that the Water absorption complished by spraying a solution or dispersion of the paelty thereef ranges from 0 t0 10 Percent of le$$- In binder into the dry mixture as it is fed to the pan of a some Instances and for some P p Products rotating disc pelletizer or into a tumbling drum, or by ihg a much higher Water absorption p to 20 Percent spray drying a fluid mixture of the particles and binder, or more may be Produced but for most P p a The mixture in a plastic form may be passed through Water absorption of from 0 t0 5 or Percent is deslr extruders or otherforming or compacting equipment 40 ablefollowed by a sizing or pressing operation to produce At the Same time the Strength of the agglomerated suitably sized and shaped agglomerates each containing P g y Products is sufficient to enable them to numerous particles f h i withstand vigorous working in paint dispersers, plastic The agglomerated product thus produced is then Working mastieating equipment Without adverse dried by any suitable means until the free water content tllre attrltional effectsthereof is reduced to from about 0 to 10 percent by The Presence of relatively fine particles of hydrous eight, The r mov l of wat r f m the agglomerates silicate minerals in combination with somewhat larger serves to bond the mineralparticles together to permit particles of anhydrous silicates embodied in the indithe agglomerates to be handled and calcined. It is also idual pigmentary compositions serves to increase the found in practice that when the hydrous silicate minernumber of ig t r ect ng facets and Surfaces therein als in the mixture are of somewhat smaller average size he eby the isible light reflectance of the pigments than the particles of anhydrous mineral therein, the greatly exceeds those of the minerals contained mixture is more plastic and workable when forming the therein. As a result, when they are dispersed in a liquid agglomerates due to the better packing of the particles medium having a refractive index approximating the together. Moreover, the amount of the inorganic refractive indices of the silicate minerals contained, binder required in producing the agglomerates may be such as tricresyl phosphate, the pigments exhibit a high reduced. The density and strength of the resulting ag- Opacity and, in the event colorants are incorporated glomerates is accordingly increased so that they have therein, they also have distinctive and brilliant colors. less tendency to crumble or fall apart during the subse- In order to illustrate typical embodiments of the presquent operations of drying and calcining. ent invention the following examples are cited:

Specific Gravity EXAMPLE MINERAL "/iSubst. Min/C Deter- Calcu- %reduc- 'Zwaier mined lated tion abs.

No. l Feldspar 0 lO/l 2.37 2.63 9.9 2.2

Hill 2.26 i4.i 0

No. 2 Al-Sil-Ate L0 40 Hill 100 2.3! .61 11.5 3.3 it) Ill/I130 2.31 .63 12.2 1.5

Specific Gravity EXAMPLE MINERAL '7zSubst. Min./C Deter- Calcu- /zreduc Zrwater mined lated tion abs.

No. 3 Asbestine 3X 40 10/1130 2.36 2.69 12.3 10 do. 2.37 2.65 10.6 0

No. 4 Mica 40 10/1100 2 22 2.70 17.8 1.0 10 11/1130 2.43 2.65 8.3 1.0

No. 5 Snow Floss 40 /1130 2.12 2.39 7.1 4.0 10 11/1130 2.32 2.57 9.7 1.7

No. 6 Perlite 40 10/1100 2.11 2.53 16.6 20.5 10/1130 2.22 2.58 14.0 3.4 10 do. 2.33 2.61 10.7 3.2 No. 7 Pyrocron 40 do. 2.20 2.66 17.3 5.8 10 (lo. 2.44 2.64 7.6 0.5

No. 8 Sheroid 40 do. 2.22 2.68 17.2 2.5 10 do. 2.38 2.65 10.2 1.3

In each of the examples cited, the anhydrous silicate material employed was a feldspar in the form of a frothflotation product consisting of a natural mixture of ablite, orthoclase and anorthite with the particles thereof ranging in size from 2 to 100 microns and an average particle size of 11 microns.

Example No. 1 is cited as a control and corresponds to the products disclosed in copending application Ser. No. 306,926. In this case 96 parts by weight of the feldspar were mixed with 4 parts by weight of an inorganic binder consisting of Bentonite L, which is a product of Georgia Kaolin Co., adjusted to 5 percent Na O content. The agglomerates produced were hand formed discs or discs pressed in a die to yield ovate cross-section discs of about 0.4 by 0.05 cm. which were thereafter dried and calcined at the temperatures and for the times indicated above.

In Examples 2 to 8 the same anhydrous silicate mineral was used but a part thereof was replaced by the indicated amounts of the hydrous silicate mineral cited. The inorganic binder again being 4 parts by weight of Bentonite L".

The Al-Sil-Ate LO of Example 2 is a product of Freeport Kaolin Co. and is a water-fractionated kaolinite of the phyllosilicates having an average particle size of 3.5 microns, an average refractive index of 1.56 and a density of 2.58.

The Asbestine 3X of Example 3 is a product of International Talc Co. consisting principally of tremolite of the amphibole group of the inosilicates with accessory minerals chlorite, serpentine and antigorite of the phyllosilicates. The product has an average particle size of 10 microns, and average refractive index of about 1.62 and a specific gravity of 2.78. lts color is white.

The mica used in Example 4 was dry ground mica schist, 100 percent passing a 200 mesh U.S. Standard sieve or 74 microns and had a specific gravity of 2.78 and a refractive index of 1.6. lts color was gray.

The Snow Floss of Example 5 is a product of Johns-Manville Corp. and is a diatomite representative of opal. It has a predominance of particles in the range of l to 4 microns, a specific gravity of 2.10, an average refractive index of 1.43 and is of a buff to pink color.

The perlite of Example 6 is a crude product of Johns- Manville Corp. having a specific gravity of 2.4 and an average particle size of about 100 microns analyzing 2.8 percent loss at 1000C, 73.0 S10 13.3 percent A1- 0 4.04 percent Na O and 4.81 percent K 0 with other lesser oxides.

The Pyrocron of Example 7 is a product of Pfizer Inc.

and is basically pyrophyllite with minor amounts of muscovite (mica) having a specific gravity of 2.71, an average particle size of 1 1 microns and an average refractive index of 1.59. It has a pink color.

The Sheroid used in Example 8 is a product of Pfizer Inc. and is a chlorite and muscovite mixed mineral called sheridanite. It has a specific gravity of 2.75, a refractive index of about 1.6 and an average particle size of 10 microns. It has a buff color.

It will be noted from the results obtained in the examples cited above that the reduction. in the specific gravity and the water absorption characteristics of the pigments vary considerably depending upon the calcining conditions. Thus in Example 6 the water absorption was reduced from above 20 percent to below 4 percent upon an increase in the calcining temperature of only 30C. The relatively large size of the particles of perlite used in Example 6 as compared with the particles of feldspar therein also contributed to the resulting high water absorption of the product. Pigments having a water absorption above 10 percent may be used as thickening agents or absorbents.

Ordinarily, there is a greater reduction in the specific gravity of the product with an increase in the proportion of the hydrous silicate to the anhydrous silicate in the product. Furthermore, depending on the calcining conditions a range of specific gravity reduction and water absorption characteristics may be attained. Accordingly, it is possible to vary and control the properties of the pigmentary compositions to obtain products having a reduction in specific gravity of from 5 to 40 percent and a water absorption from 0 up to 10 percent.

All of the products obtained in accordance with the foregoing examples exhibited considerably increased opacity as compared with those of the silicate minerals of which they are composed. The color of the products varied from brilliant white in Example 3 to gold in Example 4 and pink in Examples 7 and 8. On the other hand, the color of the compositions can be controlled and varied as desired by the addition of opacifying agents, colorants or the like as described in copending application Ser. No. 356,055. Thus, as indicated above in the table of General and Preferred compositions of the products, up to 20 percent of the composition may consist of opacifiers or colorants and other modifiers. When colored opacifying agents or modifiers are employed, substantially any suitable inorganic colorant may be used. Such white opacifiers as titanium dioxide, zirconium oxide, zirconium silicate, zirconium double silicates, zinc oxide, antimony oxide and tin oxide are representatives whereas color producing agents such as iron oxide, manganese oxide, lead chromate, ultramarine, and ceramic colorants of various and complex composition may be used. it is therefore possible to produce pigmentary compositions in accordance with the present invention having a whole spectrum of colors, shades and tints as desired.

It will therefore be apparent that the color,.composition and properties of products embodying the present invention are capable of wide variation. In view thereof it should be understood that the particular examples disclosed and described above are intended to be illustrative only and are not intended to limit the scope of the invention.

I claim:

1. A pigmentary composition comprising calcined agglomerates consisting essentially of the following in parts by weight Anhydrous Silicate Mineral from 40 to 89 Hydrous Silicate Mineral from It) to 50 Inorganic Binder from l to l average size in the range of from 1.5 to 20 microns, said agglomerates ranging in size from about 20 microns to one centimeter and having a specific gravity at least percent below that of the minerals contained therein.

2. A pigmentary composition as defined in claim 1, wherein the constituents thereof are present in the following proportions in parts by weight Anhydrous Silicate Mineral from 54 to 78 Hydrous Silicate Mineral from to 40 Inorganic Binder from 2 to o 3. A calcined pigmentary composition as defined in claim 1 having a water absorption not exceeding 10 percent by weight.

4. A calcined pigmentary composition as defined in claim 1 wherein said hydrous silicate mineral is selected from the group consisting of phyllosilicates, sorosilicates, tectosilicates, the amphibole group of inosilicates, perlite and the non-swelling montmorillonites, and mixtures thereof.

5. A calcined pigmentary composition as defined in claim 1 wherein said anhydrous silicate mineral is selected from the group consisting of silica; the silicates of berylium, magnesium, and calcium; and the alumino silicates of lithium, berylium, barium, sodium, potassium; and mixtures thereof.

6. A calcined pigmentary composition as defined in claim 1 wherein the average particle size of the anhydrous silicate mineral is from about 2 to 20 microns.

7. A calcined pigmentary composition as defined in claim 1 wherein the anhydrous silicate mineral is feldspar.

8. A calcined pigmentary composition as defined in claim 1 wherein said inorganic binder is an alkali silicate.

9. A calcined pigmentary composition as defined in claim 1 wherein said inorganic binder is an expanding lattice montmorillonite.

10. A calcined pigmentary composition as defined in claim 1 wherein said inorganic binder is a glassy phosphate containing from 4 to phosphorous atoms per molecule.

11. A calcined pigmentary composition as defined in claim 1 wherein an opacifying agent is present in the composition in an amount up to 20 percent by weight of the product.

12. A calcined pigmentary composition as defined in claim I] in which said opacifying agent is an inorganic colorant present in amounts up to 10 percent by weight.

13. A calcined pigmentary composition as defined in claim 1 wherein said anhydrous silicate is feldspar, said hydrous silicate is tremolite and said inorganic binder is an expanding lattice montmorillonite.

l l l UNITED STATES PATENT @FFMIE CERTIFICATE ctcm Patent No. 18 2574 Dated December 10. 197 1 Inventor(s) Thomas Howard Ferrigno It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 8, Line 38, change "is" to comprises [SEAL] Attest:

RUTH C. MASON C. MARSHALL DAWN Arresting Officer Commissioner oj'Parents and Trademarks 

1. A PIGMENTARY COOPOSITION COMPRISING CALCINED AGGLOMERATES CONSISTING ESSENTIALLY OF THE FOLLOWING IN PARTS BY WEIGHT ANHYDROUS SILICATE MINERAL FROM 40 TO 89 HYDROUS SILICATE MINERAL FROM 10 TO 50 INORGANIC BINDER FROM 1 TO 10 SAID INORGANIC BINDER BEING SELECTED FROM THE GROUP CONSISTING OF SODIUM POLYPHOSPHATES, EXPANDING LATTICE MONTMORILLONITE AND SOLUBLE SILICATES OF SODIUM, POTASSIUM AND LITTICE MONTMORILL ANHYDROUS SILICATE MINERALS BEING IN THE FROM OF PARTICLES HAVING AN AVERAGE SIZE IN THE RANGE OF RROM 2 TO 20 MICRONS AND SAID HYDROUS SILICATE MINERALS BEING IN THE FORM OF PARTICLES HAVING AN AVERAGE SIZE IN THE RANGE OF FROM 1.5 TO 20 MICRONS, SAID AGGLOMERATES RANGING IN SIZE FROM ABOUT 20 MICRONS TO ONE CENTIMETER AND HAVING A SPECIFIC GRAVITY AT LEAST 5 PERCENT BELOW THAT OF THE MINERALS CONTAINED THEREIN.
 2. A pigmentary composition as defined in claim 1, wherein the constituents thereof are present in the following proportions in parts by weight
 3. A calcined pigmentary composition as defined in claim 1 having a water absorption not exceeding 10 percent by weight.
 4. A calcined pigmentary composition as defined in claim 1 wherein said hydrous silicate mineral is selected from the group consisting of phyllosilicates, sorosilicates, tectosilicates, the amphibole group of inosilicates, perlite and the non-swelling montmorillonites, and mixtures thereof.
 5. A calcined pigmentary composition as defined in claim 1 wherein said anhydrous silicate mineral is selected from the group consisting of silica; the silicates of berylium, magnesium, and calcium; and the alumino silicates of lithium, berylium, barium, sodium, potassium; and mixtures thereof.
 6. A calcined pigmentary composition as defined in claim 1 wherein the average particle size of the anhydrous silicate mineral is from about 2 to 20 microns.
 7. A calcined pigmentary composition as defined in claim 1 wherein the anhydrous silicate mineral is feldspar.
 8. A calcined pigmentary composition As defined in claim 1 wherein said inorganic binder is an alkali silicate.
 9. A calcined pigmentary composition as defined in claim 1 wherein said inorganic binder is an expanding lattice montmorillonite.
 10. A calcined pigmentary composition as defined in claim 1 wherein said inorganic binder is a glassy phosphate containing from 4 to 100 phosphorous atoms per molecule.
 11. A calcined pigmentary composition as defined in claim 1 wherein an opacifying agent is present in the composition in an amount up to 20 percent by weight of the product.
 12. A calcined pigmentary composition as defined in claim 11 in which said opacifying agent is an inorganic colorant present in amounts up to 10 percent by weight.
 13. A calcined pigmentary composition as defined in claim 1 wherein said anhydrous silicate is feldspar, said hydrous silicate is tremolite and said inorganic binder is an expanding lattice montmorillonite. 